is a person that is in the closet who either doesn’t realize he/she is gay but is questioning his/her sexuality intensely, knew he/she is gay but can’t come to terms with it, or a person that has come to terms with their sexuality but was fearful of possible social repercussions of being gay

Jimmy was a closet case because before he came out, he had trouble realizing that he was gay.

A closet homosexual is what most gay supporters are. These supposedly "straight" people spend all their time defending homosexuality that it's clear that they must be gay themselves hence their obsession with it. They call anyone who finds disgust with homosexuality a "bigot" even if they don't hate the gay person themselves. Their common argument (which is also illogical) against "gay haters" is that they must be gay themselves because they find the concept of two guys pounding each other hard in the ass repulsive. Perhaps it's these gay defenders who are gay themselves?

Jimmy: "Anyone who doesn't find two men kissing cool is a bigot and homophobe and probably a closet case!" (meaning that gays hate themselves)

Jack: "Yeah I agree! I'm a straight man but I love gays!"

*Jack and Jimmy walk away from the crowd that they were preaching too and then start sucking each other's cocks*